Clean up the semget example. Clean up the return values of semop function.

programs/shell.c

@@ -24,7 +24,7 @@
 #include <ctype.h>
 
 /// Maximum length of commands.
-#define CMD_LEN 32
+#define CMD_LEN 64
 /// Maximum lenght of the history.
 #define HISTORY_MAX 10
 
@@ -155,7 +155,7 @@ static inline void __prompt_print()
     } else {
         HOSTNAME = buffer.nodename;
     }
-    printf(FG_GREEN "%s" FG_WHITE "@" FG_CYAN "%s " FG_BLUE_BRIGHT "[%02d:%02d:%02d]" FG_WHITE " [%s] " FG_WHITE_BRIGHT "%% ",
+    printf(FG_GREEN "%s" FG_WHITE "@" FG_CYAN "%s " FG_BLUE_BRIGHT "[%02d:%02d:%02d]" FG_WHITE " [%s] " FG_WHITE_BRIGHT "\n-> %% ",
            USER, HOSTNAME, timeinfo->tm_hour, timeinfo->tm_min, timeinfo->tm_sec, CWD);
 }